Diabetes mellitus is a chronic metabolic disease characterized by high levels of blood sugar in afflicted individuals. Long-term elevated sugar levels in the blood can lead to serious damage to many parts of the body, including blood vessels, kidney, and the nervous system. Because of rapid economic growth and urbanization, an increasing population of the world adopts a high-carbohydrate diet and a sedentary life style, which are major factors contributing to a global epidemic of diabetes. According to the World Health Organization, more than 347 million people worldwide live with diabetes, and an estimated 1.5 million deaths were directly caused by diabetes in 2012 alone. A safe and effective method for long-term management of blood sugar levels is therefore in urgent need.
Currently, the most widely used antidiabetic therapies include insulin, insulin stimulators, and insulin sensitizers, all of which act on insulin, a peptide hormone, or its interacting partners in the insulin signaling pathway that regulates sugar metabolism in the body. These standard anti-diabetic medications are far from fulfilling the immense needs of patients suffering from high blood sugar levels. Insulin, for example, has to be administered by injection or via a continuous intravenous pump. Small-molecule antidiabetic drugs, such as sulphonylurea and metformin, can be administered orally, but they are associated with side effects, such as gastrointestinal irritation and increased burden to the liver. Inconvenience of administration routes and undesirable side effects over extended duration of treatment greatly compromise patients' quality of life and render adherence to the therapeutic regimens rather challenging. As a result, alternative or supplementary means for lowering blood sugar are constantly sought after to satisfy the unmet patient needs.
Herbal medicine and nutritional supplements have long been widely applied by many cultures throughout the world to improve or maintain bodily functions. Traditional Chinese Medicine relies heavily on empirically-tested folk herbal medicines to treat human illnesses. Several herbs from Traditional Chinese Medicine possess hypoglycemic (or blood sugar lowering) effects, including Cyclocarya paliurus (wheel wingnut, or Qing qian liu in Chinese), Puerariae lobatae Radix (kudzu root, or Ge gen in Chinese) and Polygonati odorati Rhizoma (Yu zhu in Chinese).
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